TW201803963A - Method for polishing silicon substrate and polishing composition set - Google Patents

Abstract

Provided are: a polishing method which is applicable in common to a plurality of silicon substrates that have resistivities different from each other; and a polishing composition set which is used in this polishing method. A silicon substrate polishing method according to the present invention comprises supplying of a first polishing slurry S1 and a second polishing slurry S2 in this order to a silicon substrate to be polished such that the polishing slurries are switched during the polishing of the silicon substrate. The first polishing slurry S1 contains abrasive grains A1 and a water-soluble polymer P1. The polishing efficiency of the first polishing slurry S1 is higher than the polishing efficiency of the second polishing slurry S2.

Description

Polishing method of silicon substrate and composition set for polishing

The present invention relates to a polishing method for polishing a plurality of silicon substrates having mutually different resistivities, and a polishing composition set used in the polishing method. This application claims priority based on Japanese Patent Application No. 2016-39066 filed on March 1, 2016, and the entire contents of this application are incorporated in this specification for reference.

The surface of a silicon wafer used for the manufacture of semiconductor products is generally polished into a high-quality mirror surface after grinding (rough grinding step) and polishing step (precision grinding step). The above-mentioned polishing step typically includes a pre-polishing step (preliminary grinding step) and a finishing polishing step (finishing grinding step). Technical documents related to polishing of silicon wafers are listed in, for example, Patent Documents 1 to 3.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2010/013390

[Patent Document 2] Japanese Patent Application Publication No. 2014-103398 Report

[Patent Document 3] Japanese Patent Application Laid-Open No. 2006-324417

In recent years, demand for low-resistivity silicon wafers has increased. A low-resistivity silicon wafer is processed into a mirror surface by, for example, grinding and polishing as described above, and then an epitaxial layer is grown on the surface, and used as a substrate for power semiconductor device manufacturing. The low-resistivity silicon wafer is generally doped with a dopant at a high concentration. As a dopant, boron is used in a p-type silicon wafer system, and phosphorus, arsenic, or the like is used in an n-type silicon wafer system.

Such low-resistivity silicon wafers are known to be more difficult to grind than conventional silicon wafers. Here, the so-called ordinary silicon wafer generally means a resistivity of 1Ω. cm and below 100Ω. cm, typically 100 ohm resistivity. Silicon wafers around cm. In addition, low-resistivity silicon wafers have different degrees of polishing, and silicon wafers with lower resistivity (higher dopant concentration) tend to be more difficult to polish.

Such polishing of a plurality of silicon wafers with different resistivities, in order to efficiently finish various types of silicon wafers to a desired surface quality, is currently applicable to mutually different grinding processes. For example, at least a part of the polishing slurry used, the polishing apparatus, the polishing conditions (for example, the polishing time), and the like are performed differently.

It is therefore an object of the present invention to provide a universally applicable A method for polishing a plurality of silicon substrates having different resistivities. A related other object is to provide a polishing composition set which can be suitably used by the polishing method.

The polishing method provided in this specification includes sequentially supplying the first polishing slurry S ₁ and the second polishing slurry S ₂ to the silicon substrate of the polishing target during the polishing of the silicon substrate in order. Here, the first polishing slurry S ₁ contains abrasive particles A ₁ and a water-soluble polymer P ₁ . As the first polishing slurry S ₁ , one having a polishing energy higher than that of the second polishing slurry S ₂ is used.

According to this polishing method, the surface roughness of a plurality of silicon substrates having different resistivities from each other can be reduced. Therefore, by applying the above-mentioned polishing method, it is possible to efficiently manufacture a plurality of silicon substrates having different resistivities from each other. The above-mentioned polishing method can also play a role of simplifying the polishing equipment in the manufacture of the plurality of silicon substrates or increasing the operation rate of the polishing device.

Preferably, the polishing method disclosed herein of the same states, the water-soluble polymer in the above-described first polishing slurry S ₁ P ₁ of not less than 0.001 wt% concentration. According to this state, even if a silicon substrate with a high resistivity (for example, a resistivity of 1 Ω.cm or more) is polished by the same polishing process as a silicon substrate with a low resistivity (for example, the resistivity is less than 0.005 Ω.cm), it can be better To reduce the surface roughness of the high-resistivity silicon substrate.

In the state of the technology disclosed herein, it is preferred that the water-soluble polymer P ₁ contains a vinyl alcohol-based polymer chain. In this aspect, the applicable effects of the present invention can be better exerted.

In another aspect of the technology disclosed herein, it is preferred that the water-soluble polymer P ₁ includes an N-vinyl polymer chain. When the first polishing slurry S ₁ containing such a water-soluble polymer P ₁ is used, even if the high-resistivity silicon substrate is polished by the same polishing process as the low-resistivity silicon substrate, the above-mentioned high can be reduced. Surface roughness of the silicon substrate with resistivity. Moreover, even if the polishing process that can reduce the surface roughness of the high-resistivity silicon substrate is applied to a low-resistivity silicon substrate, the low-resistivity silicon substrate can be efficiently polished.

In a preferred aspect of the polishing method disclosed herein, the first polishing slurry S ₁ includes an alkali metal hydroxide as the basic compound B ₁ . According to this aspect, even if the high-resistivity silicon substrate is polished by the same polishing process as the low-resistivity silicon substrate, the surface roughness of the high-resistivity silicon substrate can be reduced well. Moreover, even if the polishing process that can reduce the surface roughness of the high-resistivity silicon substrate is applied to a low-resistivity silicon substrate, the low-resistivity silicon substrate can be efficiently polished.

In the polishing method disclosed herein, the second polishing slurry S _{2 is} preferably one containing abrasive particles A ₂ and a water-soluble polymer P ₂ . The concentration is preferably above _{2 2} 2 polishing slurry of the water-soluble polymer S is higher than the concentration of P in the above-described first polishing slurry S ₁ P ₁ of the water-soluble polymer. By using such a second polishing slurry S ₂ , it is possible to efficiently realize a high-quality surface for a plurality of silicon substrates having different resistivities from each other.

In the aspect in which the second polishing slurry S ₂ contains abrasive particles A ₂ , the content of the abrasive particles A ₂ is preferably 0.5% by weight or less. According to such a second polishing slurry S ₂ , it is possible to efficiently realize a high-quality surface for a plurality of silicon substrates having different resistivities.

In a preferred aspect of the polishing method disclosed herein, the BET diameter of the above-mentioned abrasive particles A ₁ contained in the above-mentioned first polishing slurry S ₁ is less than 60 nm. According to this aspect, it is possible to efficiently realize a high-quality surface for a plurality of silicon substrates having different resistivities. The BET diameter of the abrasive particles A ₂ contained in the second polishing slurry S ₂ is also preferably less than 60 nm.

The polishing method disclosed herein can reduce the surface roughness of a plurality of types of silicon substrates having different resistivities from each other. Therefore, for example, the polishing method can be commonly applied to a plurality of types of silicon substrates having a resistivity difference of more than 100 times. In a preferred state, the plurality of silicon substrates described above may include a resistivity of 1Ω. Silicon substrate above cm and resistivity have not reached 0.005Ω. cm silicon substrate. The polishing method disclosed herein can be better applied to the polishing (such as finishing polishing) of these silicon substrates.

According to the present specification, a polishing composition set for use in any of the polishing methods disclosed herein is also provided. The polishing composition of the polishing kit comprising _a first slurry S or a liquid concentrate composition Q ₁ of the first and the second polishing slurry S ₂ or a second concentrate composition Q _2. Here, the first composition Q ₁ and the second composition Q ₂ are stored separately from each other. The polishing method disclosed herein can be preferably implemented using the polishing composition set having this configuration.

The matters disclosed in this specification include the polishing composition used in any of the polishing methods disclosed herein and are the polishing composition of the above-mentioned first polishing slurry S ₁ or its concentrated liquid. The polishing composition can be preferably used, for example, as the first composition Q ₁ constituting the polishing composition set disclosed herein.

The matters disclosed in this specification include the polishing composition used in any of the polishing methods disclosed herein and are the polishing composition of the above-mentioned second polishing slurry S ₂ or its concentrated liquid. The polishing composition can be preferably used, for example, as the second composition Q ₂ that constitutes the polishing composition set disclosed herein.

Hereinafter, preferred embodiments of the present invention will be described. It is to be noted that the implementation of the present invention other than the matters specifically mentioned in this specification is a person skilled in the art can grasp design matters based on conventional technology in the field. The present invention can be implemented based on the contents disclosed in this specification and technical knowledge in the field.

The technique disclosed in this article is suitable for polishing with a silicon substrate as a polishing object. It is particularly suitable for polishing with silicon wafers as polishing targets. A typical example of a silicon wafer referred to herein is a silicon single crystal wafer, such as a silicon single crystal wafer obtained by slicing a silicon single crystal ingot. The polishing target surface in the technology disclosed herein is typically a surface made of silicon.

The polishing method disclosed in this paper can be applied to the polishing step of a silicon substrate. Prior to the polishing step (polishing step) disclosed herein, the above silicon substrate may be subjected to general processing such as grinding or etching in a step upstream of the polishing step, which is applicable to the silicon substrate.

In addition, in the following description, regardless of the polishing slurry used in any polishing stage, for example, regardless of the first polishing slurry S ₁ or the second polishing slurry S ₂ , it is generally used as the polishing slurry used in the polishing method disclosed herein. In the case of the term "grinding slurry" for the term of material.

The polishing method disclosed herein includes a polishing step of sequentially supplying the first polishing slurry S ₁ and the second polishing slurry S ₂ to the silicon substrate of the polishing target during the polishing of the silicon substrate in order. This polishing step is typically performed on the same platen, and the first step (first polishing step) of polishing the object to be polished with the first polishing slurry S ₁ and the second polishing slurry S _{2 are} sequentially performed in this order. The second stage (the second grinding stage) of the product is carried out as it is. That is, the first stage and the second stage are performed without moving the object to be polished to another polishing device or other platen. The first stage and the second stage are performed immediately after the same object to be polished (that is, successively). However, a plurality of grinding objects in each grinding stage are simultaneously and concurrently ground, that is, batch grinding may be performed.

<First polishing slurry S ₁ >

The first polishing slurry S ₁ contains abrasive particles A ₁ and a water-soluble polymer P ₁ , and typically further contains water.

(Abrasive grain A ₁ )

The abrasive particles have the function of physically polishing the surface of the silicon substrate. The first polishing slurry S _{1 in} the technique disclosed herein contains abrasive particles A ₁ . The material or properties of the abrasive grains A _{1 are} not particularly limited, and can be appropriately selected according to the purpose of use or the state of use. Examples of the abrasive particles A ₁ include inorganic particles, organic particles, and organic-inorganic composite examples. Specific examples of the inorganic particles include silicon oxide particles, aluminum oxide particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconia particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and iron oxide (Bengala) particles. Oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate or barium carbonate. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles, polyacrylonitrile particles, and the like. Among these, inorganic particles are preferred. The abrasive grains A ₁ may be used singly or in combination of two or more kinds.

The abrasive particles A _{1 are} preferably inorganic particles. Among them, particles made of metal or semi-metal oxides are preferred, and silicon oxide particles are particularly preferred. The technique disclosed herein can better use the state that the abrasive grains A ₁ contained in the first polishing slurry S ₁ are substantially made of silicon oxide particles. Herein called "substantially" means the weight of the particles constituting the abrasive grains 95 of the A _1% or more (preferably 98 wt% or more, more than 99 wt%, may also be 100% by weight) of silicon oxide particles.

Specific examples of the silica include colloidal silica, fumed silica, and precipitated silica. The silica particles can be used singly or in combination of two or more kinds. Based on the viewpoint that the surface of the object to be polished is less prone to scratches, and that it can further exert good polishing performance, colloidal silica is particularly preferred. As the colloidal silica, colloidal silica or an alkoxide-based colloidal silica produced by, for example, water glass (sodium silicate) by an ion exchange method can be preferably used. The so-called alkoxide colloidal silica is a colloidal silica produced by a hydrolysis and condensation reaction of an alkoxysilane. Colloidal silica can be used alone or in combination of two or more.

The true specific gravity of the silicon oxide constituting the silicon oxide particles is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more. By increasing the true specific gravity of silicon oxide, there is a tendency to increase the polishing power. From this viewpoint, particularly preferred are silica particles having a true specific gravity of 2.0 or more, such as 2.1 or more. The upper limit of the true specific gravity of silicon oxide is not particularly limited, and is typically 2.3 or less, for example, 2.2 or less. The true specific gravity of silica can be measured by a liquid replacement method using ethanol as a replacement liquid.

The BET diameter of the abrasive grains (typically silicon oxide particles) A ₁ contained in the first polishing slurry S ₁ is not particularly limited. From the viewpoint of polishing efficiency and the like, the BET diameter is preferably 5 nm or more, more preferably 10 nm or more, and particularly preferably 20 nm or more, such as 25 nm or more. From the viewpoint of obtaining a higher polishing effect, abrasive particles A ₁ having a BET diameter exceeding 30 nm can be preferably used. For example, abrasive grains A ₁ having a BET diameter of 32 nm or more can be preferably used. In addition, from the viewpoint of preventing scratches and the like, the BET diameter of the abrasive grains A ₁ is preferably 100 nm or less, more preferably 80 nm or less, still more preferably 70 nm or less, such as 60 nm or less. The technique disclosed herein can be implemented in a manner that the BET diameter of the abrasive particles A ₁ is preferably less than 60 nm, more preferably 55 nm or less, and even more preferably 45 nm or less, such as 40 nm or less. By using the first polishing slurry S ₁ containing the abrasive grains A ₁ for polishing (typically, finishing polishing), a high-quality surface can be efficiently obtained for a plurality of silicon substrates having different resistivities.

The BET diameter in this specification means the specific surface area (BET value) measured by the BET method, and the BET diameter (nm) = 6000 / (true density (g / cm ³ ) × BET value (m ² / g) ). For example, in the case of silicon oxide particles, the BET diameter can be calculated from the BET diameter (nm) = 2727 / BET value (m ² / g). The measurement of the specific surface area can be performed using, for example, a surface area measuring device manufactured by MICRO MATERIALS, under the trade name "Flow Sorb II 2300".

The shape (outer shape) of the abrasive grain A ₁ may be spherical or non-spherical. Specific examples of the non-spherical particles include a peanut shape (that is, a shape of a groundnut shell), a cocoon shape, a gold candy shape, a football shape, and the like. For example, abrasive grains A ₁ whose particles are mostly peanut-shaped can be preferably used.

Although not particularly limited, the average value of the major axis / minor axis ratio (average aspect ratio) of the abrasive grains A ₁ is in principle 1.0 or more, preferably 1.05 or more, and more preferably 1.1 or more. By increasing the average aspect ratio, a higher polishing rate can be achieved. The average aspect ratio of the abrasive grains A ₁ is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less from the viewpoint of reducing scratches and the like.

The shape (outer shape) or average aspect ratio of the abrasive grain A ₁ can be grasped by, for example, observation with an electron microscope. The specific order of grasping the average aspect ratio is, for example, using a scanning electron microscope (SEM), to draw the smallest rectangle circumscribed in each particle image for a predetermined number (for example, 200) of silicon oxide particles that can identify the shape of independent particles. . Next, for the rectangle drawn on each particle image, the value of the length of the long side (the value of the long diameter) divided by the length of the short side (the value of the short diameter) is used as the length / length ratio (aspect ratio). ). The average aspect ratio can be obtained by arithmetically averaging the predetermined number of particle aspect ratios.

The content of the abrasive particles A ₁ contained in the first polishing slurry S ₁ is not particularly limited. In the same state, the above content is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, such as 0.2% by weight or more. By increasing the content of the abrasive particles A ₁ , a higher polishing energy rate can be achieved. In addition, from the viewpoint of removability from the object to be polished, the above content is usually preferably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and further preferably 3% by weight or less, such as 2% %the following.

(water)

The first polishing slurry S ₁ typically contains water. As the water, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like can be preferably used. To try to avoid obstacles in the first polishing slurry S ₁ containing the role of the other components, water is preferably used, for example, the total content of transition metal ions is 100ppb or less. For example, ion exchange resin can be used to remove impurity ions, filtration can be used to remove foreign matter, and distillation can be used to improve the purity of water.

(Water-soluble polymer P ₁ )

The first polishing slurry S ₁ contains a water-soluble polymer P ₁ . As the water-soluble polymer P ₁ , a polymer having at least one functional group selected from a cationic group, an anionic group, and a nonionic group in a molecule may be used alone or in combination of two or more kinds. More specifically, for example, one selected from polymers having a hydroxyl group, a carboxyl group, a fluorenyloxy group, a sulfo group, a primary ammonium structure, a heterocyclic structure, a vinyl structure, a polyoxyalkylene structure, and the like can be used. One or two or more polymers are used as the water-soluble polymer P ₁ . From the viewpoints of reducing aggregates and improving detergency, non-ionic polymers can be suitably used as the water-soluble polymer P ₁ .

Non-limiting examples of polymers that can be used as the water-soluble polymer P ₁ include polyvinyl alcohol polymers (for example, polyvinyl alcohol), cellulose derivatives (for example, hydroxyethyl cellulose), and pullulan ) Derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and the like. Non-limiting examples of nitrogen atom-containing polymers include polymers containing N-vinyl monomer units such as N-vinyllactam or N-vinyl chain amide, imine derivatives, and N- ( Polymers of monomer units of meth) acrylfluorene type; etc.

In a preferred aspect of the technology disclosed herein, the water-soluble polymer P ₁ includes at least a vinyl alcohol-based polymer chain. By performing the first-stage polishing using this first polishing slurry S ₁ , the surface roughness of a plurality of silicon substrates having different resistivities can be efficiently reduced.

As used herein, the "vinyl alcohol-based polymer chain" refers to a polymer chain having vinyl alcohol units (hereinafter also referred to as "VA units") as the main repeating unit. In addition, the term "main repeating unit" in this specification means a repeating unit contained in an amount of more than 50% by weight unless otherwise specified. The above-mentioned VA unit refers to a structural part corresponding to a structure resulting from the polymerization of vinyl alcohol of vinyl alcohol (CH ₂ = CH-OH). The above-mentioned VA unit is specifically a structural part represented by a chemical formula "-CH ₂ -CH (OH)-". The VA unit can be obtained by, for example, hydrolyzing (saponifying) a repeating unit (-CH ₂ -CH (OCOCH ₃ )-) of a structure obtained by polymerizing ethylene of vinyl acetate. Hereinafter, the vinyl alcohol-based polymer chain is also referred to as "polymer chain A".

In addition, the "polymer chain" in this specification includes the concept of the polymer chain which comprises the whole polymer of one molecule, and the polymer chain which comprises a part of the polymer of one molecule.

The polymer chain A may also include only VA units as repeating units, and may include repeating units other than VA units (hereinafter also referred to as "non-VA units") in addition to the VA units. In a state where the polymer chain A includes a non-VA unit, the non-VA unit may have a member selected from, for example, ethylene oxide, carboxyl, sulfo, amine, hydroxyl, amido, amido, and nitrile. , An ether group, an ester group, and a salt of such a repeating unit of at least one structure. The polymer chain A may contain only one kind of non-VA unit, and may contain more than two kinds of non-VA units.

As a preferable example of the non-VA unit which may be contained in the polymer chain A, a vinyl monocarboxylic acid unit, that is, a repeating unit derived from vinyl monocarboxylic acid is exemplified. Examples of preferable specific examples of the above-mentioned vinyl monocarboxylic acid units include vinyl acetate units, vinyl propionate units, vinyl hexanoate units, and the like.

The mole ratio of the VA units of the repeating units constituting the polymer chain A is typically 50% or more, usually 65% or more is appropriate, preferably 75% or more, such as 80% or more . In a preferred state, the molar number ratio of the VA unit in the molar number of all repeating units constituting the polymer chain A may be 90% or more (more preferably 95% or more, such as 98% or more). The repeating units constituting the polymer chain A may also be substantially 100% AV units. Here, "substantially 100%" means to It is rare that the polymer chain A contains non-VA units.

The VA unit content (content on a weight basis) in the polymer chain A typically exceeds 50% by weight, preferably 70% by weight or more. Hereinafter, the polymer chain A having a VA unit content of 70% by weight or more is sometimes referred to as a "PVA chain". In a preferred aspect, the VA unit content in the polymer chain A is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more, for example, 98% by weight or more. The repeating units constituting the polymer chain A may also be substantially 100% VA units. Here, "substantially 100%" means that at least non-VA units are intentionally contained as repeating units constituting the polymer chain A.

The water-soluble polymer P ₁ may also replace polymer chain A or contain polymer chains other than polymer chain A in addition to polymer chain A. Here, the polymer chain not corresponding to the polymer chain A means a polymer chain having a non-VA unit as a main repeating unit. Hereinafter, a polymer chain having a non-VA unit as a main repeating unit is also referred to as "polymer chain B".

The non-VA unit constituting the polymer chain B may be, for example, a compound having a member selected from, for example, an ethylene oxide group, a carboxyl group, a sulfo group, an amine group, a hydroxyl group, an amido group, an imino group, a nitrile group, an ether group, an ester group, and Repeated units of at least one of these salts. A preferred example of the polymer chain B is a polymer chain containing an N-vinyl monomer unit described later. Among them, a polymer chain having an N-vinyl monomer unit as a main repeating unit is preferred. Hereinafter, a polymer chain using N-vinyl monomer units as a main repeating unit is also referred to as "N-vinyl polymer chain".

In a preferred aspect of the technology disclosed herein, the water-soluble polymer P ₁ may include a water-soluble polymer P _A having a polymer chain _A and a water-soluble polymer P _B having a polymer chain B. I.e., _a first polishing slurry S contained in it may be _a water-soluble polymer and the water-soluble polymer mixture P _A P _B of the water-soluble polymer P.

Non-limiting examples of the water-soluble polymer P _B include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and the like. Non-limiting examples of nitrogen atom-containing polymers include polymers containing N-vinyl monomer units such as N-vinyllactam or N-vinyl chain amidine; imine derivatives; N-containing (Meth) acrylfluorene-based monomer unit polymer; etc.

Cellulose derivatives (hereinafter also referred to as "polymers P _BA ") are polymers containing β-glucose units as the main repeating unit. Specific examples of the cellulose derivative include hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, and ethyl Hydroxyethyl cellulose, carboxymethyl cellulose and the like. Among them, hydroxyethyl cellulose (HEC) is preferred.

A starch derivative (hereinafter also referred to as "polymer P _BB ") is a polymer containing an α-glucose unit as a main repeating unit. Specific examples of the starch derivative include alpha starch, starch, carboxymethyl starch, and cyclodextrin. Among them, starch is preferred.

Polymers containing oxyalkylene units (hereinafter also referred to as "polymer P _BC ") are exemplified by polyethylene oxide (PEO), or ethylene oxide (EO) and propylene oxide (PO), or with cyclic Oxybutane (BO) block copolymer, EO and PO or random copolymer with BO, etc. Among them, a block copolymer of EO and PO or a random copolymer of EO and PO is preferred. The block copolymer of EO and PO may be a diblock copolymer, a triblock copolymer, and the like containing a PEO block and a polypropylene oxide (PPO) block. Examples of the triblock copolymer include a PEO-PPO-PEO type triblock copolymer and a PPO-PEO-PPO type triblock copolymer. Usually it is more preferably a PEO-PPO-PEO type triblock copolymer.

In addition, the term "copolymer" as used herein means a variety of copolymers including random copolymers, alternating copolymers, block copolymers, and graft copolymers, unless otherwise specified.

Examples of polymers containing monomer units of the N-vinyl type (hereinafter also referred to as "Polymer P _BD ") include those containing repeating units derived from monomers having a nitrogen-containing heterocycle (e.g., a lactam ring). polymer. Examples of such polymers P _BD include homopolymers and copolymers of N-ethylene lactamamine type monomers (for example, copolymers in which the copolymerization ratio of N-ethylene lactamamine type monomers exceeds 50% by weight), N -Homopolymers and copolymers of ethylene chain-type amidine (for example, copolymers in which the copolymerization ratio of N-ethylene chain-type amidine exceeds 50% by weight);

Specific examples of the N-vinylidene-type monomer include N-vinylpyrrolidone (VP), N-vinylpiperidone, N-vinylmorpholinone, and N-vinylcaprolactam. (VC), N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, and the like. Specific examples of the polymer containing monomer units of the N-vinyllactam type are polyvinylpyrrolidone, polyvinylcaprolactam, a random copolymer of VP and VC, and one of VP and VC Or both with other vinyl monomers (e.g. acrylic monomers, vinyl esters Monomers, etc.) random copolymers, block copolymers or graft copolymers containing polymer chains containing one or both of VP and VC (e.g., polyvinyl pyrrolidine grafted onto polyvinyl alcohol Ketone graft copolymers) and the like.

Specific examples of the N-vinyl chain fluorenamine include N-vinylacetamide, N-vinylpropylamine, N-vinylbutylamine, and the like.

Examples of the imine derivative (hereinafter also referred to as "polymer P _BE ") are homopolymers and copolymers of N-fluorenylalkyleneimine-type monomers. Specific examples of the N-fluorenylalkyleneimine-type monomer include N-ethylfluorenylethylimine, N-propylfluorenylethylimine, N-hexylmethylimine, N-benzyl Fluorenylethylimine, N-ethylfluorenylpropylimine, N-butylfluorenylethylimine, and the like. As the homopolymer of the N-fluorenylalkyleneimine-type monomer, poly (N-fluorenylalkyleneimine) or the like can be used. Specific examples are poly (N-ethylamidinoethylimine), poly (N-propylamidinoethylimine), poly (N-hexamethylideneethylimine), poly (N-benzidine) Alkyleneimine), poly (N-ethylamidinopropylimine), poly (N-butylamidinoethylimine), and the like. Examples of copolymers of N-fluorenylalkyleneimine monomers include copolymers of two or more N-fluorenylalkyleneimine monomers, or one or more N-fluorenylalkylenes. Copolymer of imine type monomer and other monomers.

Containing N- (meth) monomeric units of the polymer type of Bing Xixi group (hereinafter, also referred to as "polymer P _BF") of Example comprising N- (meth) Bing Xixi group of homopolymers of monomers and Copolymer (typically a copolymer in which the copolymerization ratio of N- (meth) acrylfluorene-based monomer exceeds 50% by weight). Examples of the N- (meth) acrylfluorenyl type monomer include a chain amidine having an N- (meth) acrylfluorenyl group and a cyclic amidine having an N- (meth) acrylfluorenyl group.

Examples of chain-like amidines having N- (meth) acrylfluorenyl are acrylamide; N-methacrylamide, N-ethylacrylamide, N-propylacrylamide, N-isopropylamine Propyl allylamine, N-butyl allylamine, N-isobutyl allylamine, N-third butyl allylamine, N-heptyl allylamine, N-octyl allylamine, N -N-monoalkylacrylamide of the third octylacrylamide, N-dodecylacrylamide, N-octadecylacrylamide, etc .; N- (2-hydroxyethyl) acrylamine Amine, N- (1,1-dimethyl-2-hydroxyethyl) acrylamide, N- (1-ethyl-hydroxyethyl) acrylamine, N- (2-chloroethyl) acrylamine Amine, N- (2,2,2-trichloro-1-hydroxyethyl) acrylamide, N- (2-dimethylaminoethyl) acrylamide, N- (3-dimethylaminopropyl Acryl) acrylamide, N- [3-bis (2-hydroxyethyl) aminopropyl] acrylamide, N- (1,1-dimethyl-2-dimethylaminoethyl) acrylamine Amine, N- (2-methyl-2-phenyl-3-dimethylaminopropyl) acrylamide, N- (2,2-dimethyl-3-dimethylaminopropyl) acrylamine Substituted N-mono of amine, N- (2-morpholinylethyl) acrylamide, N- (2-amino-1,2-dicyanoethyl) acrylamide, etc. Alkyl allylamine; N-monoalkenyl allylamine such as N-allyl allylamine; N-monoalkynyl allylamine such as N- (1,1-dimethylpropynyl) allylamine ; Aromatic amines containing aromatic groups such as N-phenylacrylamide, N-benzylacrylamide, N- [4- (phenylamino) phenyl] acrylamide; N-methylolpropene N-monohydroxyalkylacrylamide, such as fluorenamine, N-hydroxyethylacrylamide, N-hydroxypropylacrylamide; N-methoxymethacrylamine, N-ethoxymethacryl N-alkoxyalkylpropenamines such as fluorenamine, N-butoxymethacrylamide, N-isobutoxymethacrylamide; N-methoxypropenylamine N-alkoxypropenamide, such as amine, N-ethoxypropenamide, N-propoxypropenamide, N-butoxypropenamide; N-ethenylpropenamide; N-di Acetone acrylamide; methacrylamide; N-methylmethacrylamide; N-ethylmethacrylamide; N-propylmethacrylamide; N-isopropylmethacrylamide Amine, N-butylmethacrylamide, N-isobutylmethacrylamide, N-third butylmethacrylamide, N-heptylmethacrylamide, N-octylmethacrylamide, N -N-monoalkyl methacrylamide, such as third octyl methacrylamide, N-dodecyl methacrylamide, N-octadecyl methacrylamide; N- (2 -Hydroxyethyl) methacrylamide, N- (1,1-dimethyl-2-hydroxyethyl) methacrylamine, N- (1-ethyl-hydroxyethyl) methacrylamine Amine, N- (2-chloroethyl) methacrylamide, N- (2,2,2-trichloro-1-hydroxyethyl) methacrylamide, N- (2-dimethylamino Ethyl) methacrylamide, N- (3-dimethylaminopropyl) methacrylamide, N- [3-bis (2-hydroxyethyl) aminopropyl] methacrylamide , N- (1,1-dimethyl-2-dimethylamino Methyl) methacrylamide, N- (2-methyl-2-phenyl-3-dimethylaminopropyl) methacrylamide, N- (2,2-dimethyl-3-di Methylaminopropyl) methacrylamide, N- (2-morpholinylethyl) methacrylamide, N- (2-amino-1,2-dicyanoethyl) methacryl Substituted N-monoalkyl methacrylamide, such as fluorenamine; N-monoalkenyl methacrylamide, such as N-allyl methacrylamide; N- (1,1-dimethyl N-monoalkynylmethacrylamide such as propynyl) methacrylamide; N-phenylmethacrylamide, N-benzylmethacrylamine, N- [4- (phenylamine Group) phenyl] methacrylamide and other aromatic group-containing methacrylamide; N-methylolmethacrylamine, N-hydroxyethylmethacrylamine N-monohydroxyalkylmethacrylamide, such as amines, N-hydroxypropylmethacrylamide; N-methoxymethylmethacrylamide, N-ethoxymethylmethacrylamine N-alkoxyalkylmethacrylamide, such as N-butoxymethylmethacrylamide, N-isobutoxymethylmethacrylamine; N-methoxymethacrylamine N-alkoxymethacrylamide, such as amine, N-ethoxymethacrylamide, N-propoxymethacrylamide, N-butoxymethacrylamine, etc .; N-acetamidine Methacrylamide; N-diacetonemethacrylamide; N, N-dimethylacrylamide, N, N-diethylacrylamide, N, N-dipropylacrylamide, N, N-diisopropylacrylamide, N, N-dibutylacrylamide, N, N-diisobutylacrylamide, N, N-di-tert-butylacrylamide, N, N-diheptylpropenamide, N, N-dioctylpropenamide, N, N-tertiary octylpropenamide, N, N-di-dodecylpropenamide, N, N -N, N-dialkylpropenamide, such as di-octadecylpropenamide; N, N-dimethylaminoethylpropenamide, N, N-diethylaminoethylpropenamide Amine, N, N-dimethylaminopropylpropylene Amine, N, N-diethylaminopropylacrylamide, N, N-dialkylaminoalkylacrylamide; N, N-bis (2-hydroxyethyl) acrylamine, N, Substituted N, N-dialkylpropenamide, such as N-bis (2-cyanoethyl) propenamide; N, N-dienylpropene, such as N, N-diallylpropenamide Amidamine; N, N-diphenylacrylamide, N, N-dibenzylacrylamide, and other acrylamides containing aromatic groups; N, N-Dimethylmethacrylamide, N, N- N, N-dihydroxyalkylpropenamide, such as dihydroxyethylpropenamide, N, N-dihydroxypropylpropenamide; N-methyl-N-methoxypropenamide, N-methyl -N-ethoxypropenamide, N-methyl-N-propoxypropenamide, N-methyl-N-butoxypropenamide, N-ethyl-N-methoxypropenamide Amine, N-ethyl-N-ethoxypropene Fluorenamine, N-ethyl-N-butoxypropenamide, N-propyl-N-methoxypropenamide, N-propyl-N-ethoxypropenamide, N-butyl- N-alkoxy-N-alkylpropenamide, such as N-methoxypropenamide, N-butyl-N-ethoxypropenamide; N, N-diethenylpropenamide; N , N-diacetone acrylamide; N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N, N-dipropylmethacrylamide, N, N-diisopropylmethacrylamide, N, N-dibutylmethacrylamide, N, N-diisobutylmethacrylamide, N, N-di-tert-butylmethacrylamide, N, N-diheptylmethacrylamide, N, N-dioctylmethacrylamide, N, N-tertiary octylmethacrylamide, N, N-di-dodecylmethyl N, N-dialkylmethacrylamide and other N, N-di-octadecylmethacrylamide; N, N-dimethylaminoethylmethacrylamide , N, N-diethylaminoethylmethacrylamide, N, N-dimethylaminopropylmethacrylamine, N, N-diethylaminopropylmethacrylamine N, N-dialkylaminoalkylmethacrylamidine, such as amines; N, N-bis (2-hydroxy Substituted) N, N-dialkylmethacrylamide, such as methacrylamide, N, N-bis (2-cyanoethyl) methacrylamide; N, N-diallyl N, N-dienylmethacrylamide, such as methyl methacrylamide; aromatic groups such as N, N-diphenylmethacrylamine, N, N-dibenzylmethacrylamine Methacrylamide; N, N-dimethylolmethacrylamine, N, N-dihydroxyethylmethacrylamine, N, N-dihydroxypropylmethacrylamine, etc.N , N-Dihydroxyalkylmethacrylamide; N-methyl-N-methoxymethacrylamide, N-methyl-N-ethoxymethacrylamine, N-methyl- N-propoxymethacrylamide, N-methyl-N-butoxymethacrylamide, N-ethyl-N-methoxymethacrylamide, N-ethyl-N- Ethoxymethyl Allylamine, N-ethyl-N-butoxymethacrylamide, N-propyl-N-methoxymethacrylamide, N-propyl-N-ethoxymethylpropene N-alkoxy-N-alkylmethacrylamide ; N, N-diethylamidinomethacrylamide; N, N-diacetone methacrylamide and the like.

Examples of the polymer containing a linear amidine having N- (meth) acrylfluorenyl group as a monomer unit are a homopolymer of N-isopropylacrylamide and a copolymerization of N-isopropylacrylamide (For example, a copolymer in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by weight).

Examples of the cyclic amidine having N- (meth) acrylfluorenyl are N-acrylfluorenylmorpholine, N-acrylfluorenylthiomorpholine, N-acrylfluorenylpiperidine, N-acrylfluorenyl Pyrrolidine, N-methacrylfluorenylmorpholine, N-methacrylfluorenylpiperidine, N-methacrylfluorenylpyrrolidine and the like. An example of a polymer containing a cyclic amidine having an N- (meth) acrylfluorenyl group as a monomer unit is an acrylfluorenylmorpholine polymer (PACMO). Typical examples of the acrylamidomorpholine polymer are a homopolymer of N-acrylamidomorpholine (ACMO) and a copolymer of ACMO (for example, a copolymer in which the copolymerization ratio of ACMO exceeds 50% by weight). In the acrylofluorenyl morpholine polymer, the proportion of moles of all repeating units to the moles of ACMO units is usually 50% or more and 80% or more (for example, 90% or more, and typically 95%). Above) is more appropriate. All repeating units of the water-soluble polymer may be substantially composed of ACMO units.

In the same state, as the water-soluble polymer P _B , a polymer P _BD (that is, a polymer containing an N-vinyl monomer) can be preferably used. For example, a polymer P _{BD having a} repeating unit derived from an N-ethylene lactamamine type monomer derived from VP or VC as a main repeating unit can be preferably used. Among them, as a preferable polymer P _BD , a vinyl pyrrolidone polymer (PVP) is exemplified. The vinylpyrrolidone-based polymer herein refers to a homopolymer of VP and a copolymer of VP. The content of VP units (ie, repeating units derived from vinylpyrrolidone) in a vinylpyrrolidone polymer is typically more than 50% by weight, preferably 70% by weight or more, more preferably 90% by weight or more, For example, 95% by weight or more. The repeating unit constituting the vinylpyrrolidone-based polymer may be substantially 100% by weight as a VP unit.

In the case where the water-soluble polymer P ₁ contains a combination of the water-soluble polymer P _A and the water-soluble polymer P _B , the proportion of the water-soluble polymer P _{A in} the entire water-soluble polymer P ₁ may be, for example, 5 At least 10% by weight or more is usually appropriate, preferably at least 20% by weight, more preferably at least 30% by weight, for example, at least 40% by weight. P _A proportion of water-soluble polymer is usually 95 wt% or less is suitable, preferably 80 wt% or less, more preferably 70 wt% or less, for example 60 wt% or less. According to the technology disclosed herein, the proportion of the water-soluble polymer P _A which can account for the entire water-soluble polymer P ₁ is 10% by weight to 90% by weight (preferably 20% by weight to 80% by weight, such as 30% by weight). Above 70% by weight) is preferably implemented. In this aspect, the effect of reducing the surface roughness of a plurality of types of silicon substrates having different resistivities from each other can be effectively exerted.

In a preferred embodiment of the technology disclosed herein, the water-soluble polymer P ₁ may contain a copolymer having a polymer chain A and a polymer chain B in the same molecule as the water-soluble polymer P _A. The following these water-soluble polymer P _A, also known as "polymer P _A -P _B."

P _A -P _B As one preferred embodiment the polymer is a polymer of example A and the polymer chains formed by the B chain of the block copolymer.

For example a graft copolymer having a polymer chain A and B of the polymer chain as a further polymer P _A -P _B of the preferred embodiment. The above-mentioned graft copolymer may be a graft copolymer having a structure in which a polymer chain A (main chain) is grafted to a polymer chain B (side chain), or a polymer grafted in polymer chain B (main chain) Graft copolymer of chain A (side chain) structure. A graft copolymer having a structure in which a polymer chain B (side chain) is grafted to a polymer chain A (main chain) tends to exhibit higher effects.

Examples of preferred examples of the polymer chain B constituting the polymer P _A -P _{B are} a polymer chain having a repeating unit derived from the above-mentioned N-vinyl monomer unit as a main repeating unit, or a polymer chain derived from N -A repeating unit of monomer units of the (meth) acrylfluorenyl type as the main repeating polymer chain. Among them, a polymer chain having an N-vinyl monomer unit as a main repeating unit, that is, an N-vinyl polymer chain is preferable. The N-vinyl polymer chain may be a polymer chain having a copolymerization ratio of a monomer having a nitrogen-containing heterocyclic ring (typically, an N-ethylene lactam type monomer) exceeding 50% by weight. It is preferable that the content of the repeating unit derived from an N-vinyllactamide type monomer selected from N-vinylpyrrolidone (VP), N-vinylpiperidone, and N-vinylcaprolactam (VC) is more than, for example. 50% by weight of polymer chain B. For example, the polymer chain B having a VP content of more than 50% by weight, and more preferably 70% by weight or more is preferable. Hereinafter, the polymer chain B having a VP unit content of 70% by weight or more is sometimes referred to as a "PVP chain".

In the state of the technology disclosed herein, as the water-soluble polymer P ₁ , a polymer P _A -P _B having a PVP chain as the polymer chain B can be preferably used, that is, P _A -PVP. The content of VP units in the PVP chain constituting P _A -PVP is preferably 90% by weight or more, for example, 95% by weight or more, and may also be substantially 100% by weight.

As a preferred example of the above P _A -PVP, P _A -PVP whose polymer chain A is a PVA chain, that is, PVA-PVP. The VA unit content in the PVP chain constituting the PVA-PVP is preferably 90% by weight or more, for example, 95% by weight or more, and may also be substantially 100% by weight.

PVA-PVP is particularly preferably a graft copolymer having a PVA main chain and a structure grafted with PVP as a side chain, that is, a PVA main chain-PVP graft copolymer.

Weight average molecular weight of P _A water-soluble polymer (Mw) is not particularly limited. The Mw of the water-soluble polymer P _A is usually 0.2 × 10 ⁴ or more, preferably 0.4 × 10 ⁴ or more, more preferably 1 × 10 ⁴ or more, and still more preferably 1.5 × 10 ⁴ or more. With Mw of the water-soluble polymer P _A is increased, tends to increase after the polishing of the surface smoothness. The Mw of the water-soluble polymer P _A is usually 200 × 10 ⁴ or less, preferably 150 × 10 ⁴ or less, more preferably 100 × 10 ⁴ or less, and still more preferably 50 × 10 ⁴ or less. With Mw P _A of the water-soluble polymer decreases, there is _a tendency to more readily smoothly from the first polishing slurry S toward the second switch S ₂ of the polishing slurry. The Mw of the water-soluble polymer P _A may be 30 × 10 ⁴ or less, and may also be 20 × 10 ⁴ or less, for example, 10 × 10 ⁴ or less.

P _A water-soluble polymer is a polymer chain comprising a block copolymer of A and B chains of the polymer, the polymer chains constituting the Mw (i.e., a polymer chain of the polymer chain A and B of the block copolymers The Mw) of each is not particularly limited. In the same state, the Mw of each of the above polymer chains is preferably 0.1 × 10 ⁴ or more, more preferably 1 × 10 ⁴ or more, and still more preferably 1.5 × 10 ⁴ or more, such as 2 × 10 ⁴ or more. The Mw of each polymer chain is preferably 100 × 10 ⁴ or less, more preferably 50 × 10 ⁴ or less, and still more preferably 30 × 10 ⁴ or less.

When P _A water-soluble polymer is a graft copolymer comprising a polymer chain A and B of the polymer chains, the polymer chains constituting the Mw of the graft copolymer is not particularly limited.

In the same state, it is appropriate that the Mw of the polymer chain constituting the main chain of the graft copolymer is 0.1 × 10 ⁴ or more (for example, 0.2 × 10 ⁴ or more), preferably 0.4 × 10 ⁴ or more, and more preferably 1 × 10 ⁴ or more, and more preferably 1.5 × 10 ⁴ or more. The Mw of the polymer chain constituting the main chain is preferably 100 × 10 ⁴ or less, preferably 50 × 10 ⁴ or less, more preferably 30 × 10 ⁴ or less, and still more preferably 20 × 10 ⁴ or less, such as 10 × 10 ⁴ or less.

It is appropriate that Mw of the polymer chain constituting the side chain of the graft copolymer is 0.1 × 10 ⁴ or more (for example, 0.2 × 10 ⁴ or more), preferably 1 × 10 ⁴ or more, and more preferably 1.5 × 10 ⁴ or more. The Mw of the polymer chain constituting the side chain is preferably 100 × 10 ⁴ or less, preferably 50 × 10 ⁴ or less, more preferably 30 × 10 ⁴ or less, and still more preferably 20 × 10 ⁴ or less, such as 10 × 10 ⁴ or less.

Comprising a water-soluble polymer P ₁ P _B like state of the water-soluble polymer, Mw P _B of the water-soluble polymer is not particularly limited. From the viewpoints of filterability and detergency, for example, Mw is 200 × 10 ⁴ or less, preferably 170 × 10 ⁴ or less, and more preferably 150 × 10 ⁴ or less. When the Mw of the water-soluble polymer P _B is increased, the number of moles per the same amount of addition is reduced, so that the polishing rate tends to be increased. From this viewpoint, usually less than the Mw of 0.1 × 10 ⁴ P _B more appropriate water-soluble polymer, e.g., using preferably the Mw of 1 × 10 ⁴ or more water-soluble polymer P _B.

The better range of Mw may vary depending on the type of water-soluble polymer P _B varies. For example, the Mw of the water-soluble polymer P _BA and the water-soluble polymer P _BB are typically less than 200 × 10 ⁴ , preferably 170 × 10 ⁴ or less, and more preferably 150 × 10 ⁴ or less. In the same state, the Mw of the water-soluble polymer P _BA and the water-soluble polymer P _BB may be 100 × 10 ⁴ or less, for example, 50 × 10 ⁴ or less. Moreover, the Mw of the water-soluble polymer P _BA and the water-soluble polymer P _BB are typically 1 × 10 ⁴ or more, more preferably 2 × 10 ⁴ or more, still more preferably 3 × 10 ⁴ or more, and even more preferably 5 × 10 ⁴ or more, for example, 7 × 10 ⁴ or more. In the same state, the Mw of the water-soluble polymer P _BA and the water-soluble polymer P _BB may be, for example, 15 × 10 ⁴ or more, and may also be 30 × 10 ⁴ or more.

For example, the Mw of the water-soluble polymer P _BC , the water-soluble polymer P _BD, and the water-soluble polymer P _BE are preferably 50 × 10 ⁴ or less, more preferably 30 × 10 ⁴ or less. In the same state, the Mw of these water-soluble polymers may be 20 × 10 ⁴ or less, and may be 10 × 10 ⁴ or less, for example, 5 × 10 ⁴ or less. The Mw of the water-soluble polymer P _BC , the water-soluble polymer P _BD, and the water-soluble polymer P _BE are typically 0.2 × 10 ⁴ or more, preferably 0.4 × 10 ⁴ or more, and more preferably 1 × 10 ⁴ or more. , For example, 3 × 10 ⁴ or more.

The relationship between the weight average molecular weight (Mw) and the number average molecular weight (Mn) in each of the water-soluble polymers used in the water-soluble polymer P ₁ or the polymer chain constituting them is not particularly limited. From the viewpoint of preventing the occurrence of agglomerates, for example, it is preferable that the molecular weight distribution (Mw / Mn) is 10.0 or less, and more preferably 7.0 or less.

In addition, as Mw and Mn of the water-soluble polymer, values based on water-based gel permeation chromatography (GPC) (water-based, polyethylene oxide conversion) can be used.

Among the water-soluble polymers P ₁ containing polymer chain A (for example, PVA chain) and polymer chain B (for example, N-vinyl polymer chain) in the same molecule or different molecules, _one of the water-soluble polymers P ₁ The content of the polymer chain A (the proportion of the polymer chain A in the entire water-soluble polymer P ₁ ) can be set to, for example, 5% by weight or more, usually 10% by weight or more is appropriate, and preferably 20% by weight or more. , More preferably 30% by weight or more, such as 35% by weight or more. The content of the polymer chain A in the water-soluble polymer P ₁ is usually 95% by weight or less, preferably 80% by weight or less, more preferably 70% by weight or less, such as 60% by weight or less. The technology disclosed herein allows the content of polymer chain A in the water-soluble polymer P ₁ to be 5% to 90% by weight (more preferably 10% to 80% by weight, such as 20% to 70% by weight). This aspect is well implemented. By using the first polishing slurry S ₁ containing such a water-soluble polymer P ₁ , the effects of reducing the surface roughness of a plurality of silicon substrates having different resistivities from each other can be effectively exhibited.

The concentration of the water-soluble polymer P ₁ in the first polishing slurry S ₁ is not particularly limited. The concentration of the water-soluble polymer P ₁ can be, for example, 0.0001% by weight or more of the first polishing slurry S ₁ , preferably 0.0005% by weight or more, more preferably 0.001% by weight or more, and still more preferably 0.0015% by weight or more. As the concentration of the water-soluble polymer P ₁ increases, a higher quality surface tends to be obtained. On the other hand, from the viewpoint of polishing efficiency, the concentration of the water-soluble polymer P ₁ is preferably, for example, 0.1% by weight or less of the first polishing slurry S ₁ , and more preferably 0.05% by weight or less (for example, 0.01% by weight or less). In particular, from the viewpoint of efficiently polishing a plurality of silicon substrates having different resistivities from each other, the concentration of the water-soluble polymer P ₁ is preferably less than 0.01% by weight, more preferably 0.008% by weight or less, and more preferably 0.005% by weight or less. .

The content of water-soluble polymer P ₁ for the polishing abrasive grains contained in the first slurry S ₁ of A ₁ or more per 1g of 0.0002g appropriate, preferably 0.001g, more preferably at least 0.002g, 0.003 and better g or more, for example, 0.005 g or more. The content of the water-soluble polymer P ₁ is preferably 0.05 g or less, and more preferably 0.03 g or less (for example, 0.02 g or less) per 1 g of the abrasive particles A ₁ included in the first polishing slurry S ₁ .

P ₁ in the water-soluble polymer comprising a water-soluble polymer like state P _A and P _B of the water-soluble polymer, the concentration of water-soluble polymers of the first polishing slurry of S ₁ P _B may be set, for example, 0.00001% by weight The above is preferably 0.0001% by weight or more, more preferably 0.0005% by weight or more, and still more preferably 0.001% by weight or more. By increasing the concentration of water-soluble polymer P _B, there is a tendency to obtain a higher quality of the surface. On the other hand, from the viewpoint of polishing efficiency, the concentration of the water-soluble polymer P _B is preferably, for example, less than 0.1% by weight of the first polishing slurry S ₁ , and more preferably less than 0.05% by weight (for example, less than 0.01% by weight). ). In particular, from the viewpoint of efficiently polishing a plurality of silicon substrates having mutually different resistivities, the concentration of the water-soluble polymer P _B is preferably less than 0.008% by weight of the first polishing slurry S ₁ , and more preferably less than 0.005 weight. %, More preferably less than 0.003% by weight.

And, in _a water-soluble polymer P containing water-soluble polymer like state P _A and P _B of the water-soluble polymer, the water-soluble polymer P _B of the polishing abrasive grains contained in the first slurry S ₁ of A ₁ is preferably 0.0001 g or more per 1 g, preferably 0.0005 g or more, more preferably 0.001 g or more, and even more preferably 0.002 g or more, such as 0.003 g or more. In addition, the content of the water-soluble polymer P _B is preferably less than 0.05 g per 1 g of the abrasive particles A ₁ contained in the first polishing slurry S ₁ , and more preferably less than 0.03 g (for example, less than 0.02 g). Less than 0.015g.

(Basic compound B ₁ )

The first polishing slurry S ₁ preferably contains a basic compound B ₁ . The term “basic compound” used herein refers to a compound having a function of increasing the pH of an aqueous solution by dissolving it in water. As the basic compound B _1, a nitrogen-containing organic or inorganic basic compound, a hydroxide of an alkali metal, a hydroxide of an alkaline earth metal, various carbonates or bicarbonates, and the like can be used. Examples of the nitrogen-containing basic compound include a quaternary ammonium compound, a quaternary amidine compound, ammonia, an amine (preferably a water-soluble amine), and the like. These basic compounds may be used alone or in combination of two or more.

Specific examples of the alkali metal hydroxide include potassium hydroxide and sodium hydroxide. Examples of specific examples of carbonate or bicarbonate Examples include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate. Specific examples of the amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, and hexamethylene Diamine, diethylene triamine, triethylene tetramine, anhydrous piperidine, piperidine hexahydrate, 1- (2-aminoethyl) piperidine, N-methylpiperidine, guanidine, Imidazole or azoles such as triazole. Specific examples of the quaternary phosphonium compound include quaternary phosphonium hydroxide such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

As the quaternary ammonium compound, a quaternary ammonium salt (typically a strong base) such as a tetraalkylammonium salt, an alkyltrialkylammonium hydroxide, or the like can be preferably used. The anionic component in the quaternary ammonium salt may be, for example, OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , BH ₄ ⁻ and the like. As preferred example embodiment wherein an anionic based composition OH ^- the quaternary ammonium salt, i.e., a quaternary ammonium hydroxide. Specific examples of the quaternary ammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexyl hydroxide Tetraalkylammonium hydroxide, such as ammonium, and hydroxyalkyltrialkylammonium hydroxide, such as 2-hydroxyethyltrimethylamine hydroxide (also known as choline). Among these, tetraalkylammonium hydroxide is preferred, and among these, tetramethylammonium hydroxide (TMAH) is preferred.

As the basic compound B 1 S ₁ contained in the polishing slurry ₁ is preferably selected from alkali metal hydroxides, quaternary ammonium hydroxide, ammonia and the at least one basic compound. Among these, alkali metal hydroxide and quaternary ammonium hydroxide are more preferred, and alkali metal hydroxide is particularly preferred. The technique disclosed herein can be the first grinding slurry S ₁ series containing water-soluble polymers P ₁ with PVA chains and N-vinyl polymer chains (such as PVP chains) in the same molecule or different molecules, and alkali metal hydroxide The basic compound B ₁ of at least one of the compounds and quaternary ammonium hydroxide (more preferably an alkali metal hydroxide such as potassium hydroxide) is preferably implemented.

<Surfactant>

The first polishing slurry S ₁ may also contain a surfactant (typically a water-soluble organic compound having a Mw of less than 1 × 10 ⁴ ). The surfactant can help improve the dispersion stability of the first polishing slurry S ₁ or the concentrate thereof. As the surfactant, anionic or nonionic ones can be preferably used. From the viewpoint of low foamability or ease of pH adjustment, a nonionic surfactant is more preferred. Examples are oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc .; polyoxyethylene alkyl ether, polyoxyethyl alkylphenylphenyl ether, polyoxyethylene Polyoxyalkylene adducts of ethyl alkylamine, polyoxyethylene fatty acid ester, polyoxyethylene glyceryl ether fatty acid ester, polyoxyethylene sorbitan fatty acid ester, etc .; plural Non-ionic surfactants such as oxyalkylene copolymers (such as diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). The surfactant can be used singly or in combination of two or more kinds.

The Mw of the surfactant is typically less than 1 × 10 ⁴ , and it is preferably 9500 or less (for example, less than 1,000) from the viewpoints of the filterability of the polishing slurry and the cleaning property of the polishing object. In addition, the Mw of the surfactant is typically 200 or more, and from the viewpoint of the effect of reducing the turbidity level, etc., it is preferably 250 or more, and more preferably 300 or more (for example, 500 or more). The Mw of the surfactant can be a value obtained by GPC (aqueous, polyethylene glycol equivalent) or a value calculated from a chemical formula. In addition, the technique disclosed herein can be implemented in a state that the first polishing slurry S ₁ does not substantially contain the surfactant as described above.

(Chelating agent)

The first polishing slurry S ₁ may contain a chelating agent. The chelating agent functions to suppress the contamination of the object to be polished due to the metal impurities by forming the wrong ions and capturing the metal impurities that may be contained in the polishing slurry. Examples of the chelating agent include an aminocarboxylic acid-based chelating agent and an organic phosphonic acid-based chelating agent. Examples of amino carboxylic acid-based chelating agents include ethylenediamine tetraacetic acid, sodium ethylenediamine tetraacetate, nitrogen triacetic acid, sodium nitrogen triacetate, ammonium nitrogen triacetate, hydroxyethyl ethylenediamine triacetic acid, and hydroxyl groups. Ethyl ethylenediamine triacetate, diethylene triamine pentaacetic acid, sodium diethylene triamine pentaacetate, triethylene tetraamine hexaacetic acid, and sodium triethylene tetraamine hexaacetate. Examples of the organic phosphonic acid-based chelating agent include 2-aminoethylphosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, aminotris (methylenephosphonic acid), and ethylenediamine Methylphosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1- Hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxyl-1,2-diphosphonic acid, methane hydroxyphosphonic acid, 2-phosphinofluorenylbutane-1,2-dicarboxylic acid, 1-phosphinofluorenylbutane-2,3,4-tricarboxylic acid and α-methylphosphinofluorenylsuccinic acid. Among these, an organic phosphonic acid-based chelating agent is more preferable. Among them, preferred are ethylenediamine (methylenephosphonic acid), dimethylethylenetriaminepenta (methylenephosphonic acid), and dimethylethylenetriaminepentaacetic acid. As particularly preferred chelating agents, ethylenediamine (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid) are exemplified. The chelating agent may be used singly or in combination of two or more kinds.

The technique disclosed herein can be implemented using the first polishing slurry S ₁ which is substantially free of a chelating agent.

(Other ingredients)

In addition, the first polishing slurry S ₁ may further contain an organic acid, an organic acid salt, an inorganic acid, an inorganic acid salt, a preservative, an antifungal agent, and the like, as long as the effect of the present invention is not significantly hindered. Conventional additives in polishing slurry (typically polishing slurry used in polishing steps for silicon substrates).

The first polishing slurry S ₁ preferably contains substantially no oxidizing agent. The reason is that when the first polishing slurry S ₁ contains an oxidant, the surface of the polishing object is oxidized by supplying the first polishing slurry S ₁ to an object to be polished (here, a silicon substrate), and an oxide film is formed. Thereby, the polishing energy rate may be reduced. Specific examples of the oxidant referred to herein are hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, and the like. The fact that the first polishing slurry S ₁ does not substantially contain an oxidant means that at least the oxidant is not intentionally contained.

(pH)

The pH of the first polishing slurry S ₁ is typically 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher, and even more preferably 9.5 or higher, such as 10.0 or higher. When the pH of the first polishing slurry S ₁ is increased, the polishing energy efficiency tends to be increased. On the other hand, from the viewpoint of not hindering the dissolution of the abrasive grains (for example, silica particles) and suppressing the reduction of the mechanical polishing action by the abrasive grains, the pH of the first polishing slurry S ₁ is preferably 12.0 or less, and preferably 11.8 Hereinafter, it is more preferably 11.5 or less, and still more preferably 11.0 or less. The second polishing slurry S ₂ described later can also preferably adopt the same pH.

In addition, in the technology disclosed herein, the pH of the liquid composition (which may be a polishing slurry, a concentrated solution thereof, a cleaning solution described later, etc.) uses a pH meter and a standard buffer solution (phthalate pH buffer pH: 4.01 (25 ° C), neutral phosphate pH buffer pH: 6.86 (25 ° C), carbonate pH buffer pH: 10.01 (25 ° C)), after 3 points correction, put the glass electrode Enter the composition to be measured, and measure the value after stabilization for 2 minutes or longer to grasp it. As the pH meter, for example, a glass electrode type hydrogen ion concentration indicator (model F-23) manufactured by Horiba, or the equivalent thereof is used.

<Second polishing slurry S ₂ >

The second polishing slurry S ₂ contains abrasive particles A ₂ and typically further contains water, and preferably contains a water-soluble polymer P ₂ . As the water, it may be preferably used a polishing slurry S ₁ by the same.

(Abrasive grain A ₂ )

The abrasive grains A _{2 for} the second polishing slurry S _{2 may} be selected from those exemplified as the abrasive grains usable in the first polishing slurry S ₁ . The abrasive grains A ₂ may be used singly or in combination of two or more kinds. The abrasive grains A ₁ and A ₂ may be the same abrasive grains, or may be abrasive grains whose materials, sizes (for example, BET diameters), shapes, and the like are different from each other.

The abrasive particles A _{2 are} preferably inorganic particles, and among them, particles made of metal or semi-metal oxides are preferred, and silicon oxide particles are particularly preferred. The techniques disclosed herein may be contained in the polishing slurry S ₂ 2 A ₂ abrasive grains consisting essentially of silicon oxide particles to form well-like embodiment. The term "substantially" herein means that 95% by weight or more (preferably 98% by weight or more, more preferably 99% by weight or more, and 100% by weight) of the particles constituting the abrasive grains A _{2 are} silica particles. The technique disclosed herein can be implemented in a state where the abrasive particles A ₁ and A ₂ are both silica particles. For example, the same silica particles can be used as the abrasive grains A ₁ and A ₂ .

As preferred form, the abrasive grains ₂ A BET diameter of abrasive grains is preferably not less than -10nm A BET diameter ratio of ₁ + 10nm, more preferably less than -10nm + 5nm or less, and more than + 5nm less -5nm . When the BET diameter of the abrasive grains A _{1 and} the BET diameter of the abrasive grains A ₂ satisfy the above-mentioned relationship, there is a tendency that it is easy to smoothly switch from the first polishing slurry S ₁ to the second polishing slurry S ₂ . The techniques disclosed herein may be abrasive grains of BET BET A ₁ -2 nm diameter the diameter of the abrasive grains of the A ₂ + 2nm or more preferably less like state of FIG. For example, the same abrasive grains can be used for the abrasive grains A ₁ and A ₂ .

The technique disclosed herein can be used to grind particles A ₁ and A ₂ with a BET diameter of preferably 20 nm or more and less than 60 nm, more preferably 25 nm or more and 55 nm or less, and even more preferably 30 nm or more and 45 nm or less, such as 30 nm or more and 40 nm or less. Implementation. Thereby, it is possible to efficiently obtain a high-quality surface for a plurality of silicon substrates having different resistivities. When the polishing method disclosed herein is applicable to the finishing polishing of a silicon substrate, the use of the abrasive grains A ₁ and A ₂ having the above-mentioned BET diameter is particularly effective.

The content of the abrasive particles A ₂ contained in the second polishing slurry S ₂ is not particularly limited. In the same state, the content is preferably 0.01% by weight or more, more preferably 0.5% by weight or more, and still more preferably 0.1% by weight or more, such as 0.2% by weight or more. By increasing the content of the abrasive particles A ₂ , a higher polishing efficiency can be achieved. In addition, from the viewpoint of removability from the object to be polished, the above content is usually preferably 5 wt% or less, preferably 3 wt% or less, more preferably 2 wt% or less, and even more preferably 1 wt% or less, such as 0.5 % By weight or less.

In a preferred embodiment, the content of the abrasive grains A ₂ contained in the second polishing slurry S ₂ may be relative to the content of the abrasive grains A ₁ (content on a weight basis) contained in the first polishing slurry S ₁ . Its content of 75% to 125% is preferably 80% to 110%, and more preferably 90% to 105%. Thereby, there is a tendency that it is easy to smoothly switch from the first polishing slurry S ₁ to the second polishing slurry S ₂ . Like state of the polishing method disclosed herein may be S ₁ of the first polishing slurry of abrasive grains contained in the content A ₁ and the second abrasive polishing slurry S contained in the _two A ₂ content of about the same as the second example, the polishing slurry The content of the abrasive grains A ₂ contained in the material S ₂ is preferably implemented in a state in which the content of the abrasive grains A ₁ contained in the first polishing slurry S ₁ is -3% to + 3%.

(Water-soluble polymer P ₂ )

The second polishing slurry S ₂ preferably contains a water-soluble polymer P ₂ . The water-soluble polymer P _{2 to} be used is not particularly limited. For example, the water-soluble polymer P _A and the water-soluble polymer that can be exemplified from the water-soluble polymer P ₁ as the first polishing slurry S ₁ can be used. in P _B, alone or in appropriate combination of two or more. As states, P ₂ may be a water-soluble polymer with the water-soluble polymer contained in the polymer P ₁ of the same kind of polymers, or water-soluble polymer contained in the polymer P ₁ and isotype of different Mw polymers ( (Eg polymers with higher Mw).

A preferred example of the water-soluble polymer P ₂ is a cellulose derivative (polymer P _BA ). For example, HEC can be preferably used. The technology disclosed herein can be implemented better using HEC as the water-soluble polymer P ₂ alone. The technology disclosed herein can be implemented in the form of a combination of water-soluble polymer P ₂ containing HEC and other water-soluble polymers. In this aspect, the proportion of HEC in the entire water-soluble polymer P ₂ may be, for example, 30% by weight or more, more preferably 50% by weight or more, and even more preferably 80% by weight or more.

In the same state, the Mw of the water-soluble polymer P ₂ is preferably higher than the Mw of the water-soluble polymer P ₁ . The Mw of the water-soluble polymer P _{2 is} , for example, 1.5 times or more, preferably 2 times or more, and for example, 3 times or more of the Mw of the water-soluble polymer P ₁ . By doing so, it is possible to efficiently obtain a high-quality surface for a plurality of silicon substrates having different resistivities. Here, when one or both of the water-soluble polymer P ₁ and the water-soluble polymer P ₂ include a plurality of water-soluble polymers having different Mw, the comparison of the Mw is performed by comparing the water-soluble polymers P ₁ and P. ₂ Among the water-soluble polymers contained in each, the water-soluble polymers of the highest Mw type are mutually advancing.

The concentration of the water-soluble polymer P ₂ in the second polishing slurry S ₂ is not particularly limited. The concentration of the water-soluble polymer P ₂ may be, for example, 0.0005 wt% or more of the second polishing slurry S ₂ , preferably 0.001 wt% or more, more preferably 0.002 wt% or more, such as 0.005 wt% or more. As the concentration of the water-soluble polymer P ₂ increases, a higher quality surface tends to be obtained. On the other hand, from the viewpoint of polishing efficiency, the concentration of the water-soluble polymer P ₂ is preferably, for example, 0.5% by weight or less of the second polishing slurry S ₂ , more preferably 0.2% by weight or less, and more preferably 0.1% by weight or less ( For example, 0.05% by weight or less). From the viewpoint of efficiently polishing a plurality of silicon substrates having different resistivities from each other, the concentration of the water-soluble polymer P ₂ is preferably less than 0.05% by weight, more preferably 0.02% by weight or less, and still more preferably 0.015% by weight or less.

The content of the water-soluble polymer P ₂ is preferably 0.0005 g or more per 1 g of the abrasive grains A ₂ contained in the second polishing slurry S ₂ , preferably 0.002 g or more, and more preferably 0.005 g or more. And water-soluble polymer to the content of P ₂ of the second abrasive grains contained in the polishing slurry S ₂ A ₂ each preferably 1g to 0.5g, more preferably 0.3g or less, and more preferably 0.1g or less.

As states, the water-soluble polymer ₂ in the second polishing slurry S P ₂ concentration of water-soluble polymers is preferably higher than the first polishing slurry concentrations S ₁ P ₁ C _1, for example, more than 2.2 times (Preferably 1.5 times or more, more preferably 2 times or more). And preferably the second abrasive grain polishing slurry S ₂ A ₂ per 1g of the soluble polymer contained a high content of P is more than ₂ of the abrasive grains per 1g of soluble A ₁ in the first polishing slurry S ₁ contained in it The content of the molecule P ₁ is, for example, 1.2 times or more (preferably 1.5 times or more, and more preferably 2 times or more). By satisfying one or both of the above-mentioned concentrations and contents, there is a tendency that a higher-quality surface can be efficiently realized for a plurality of kinds of silicon substrates having different resistivities.

(Basic compound B ₂ )

The second polishing slurry S ₂ preferably contains a basic compound B ₂ . The basic compound B _{2 to be used is} not particularly limited. For example, the basic compound B ₂ can be used alone as an example of the basic compound B ₁ that can be used in the first polishing slurry S ₁ or can be used in combination of two or more. The basic compound B ₂ and the basic compound B ₁ may be the same compound or different compounds.

The basic compound B _{2 is} preferably a basic compound selected from at least one of an alkali metal hydroxide, a quaternary ammonium hydroxide, and ammonia. Among these, quaternary ammonium hydroxide and ammonia are more preferred, and ammonia is particularly preferred. The techniques disclosed herein may be a second polishing slurry comprising a water-soluble polymer comprising ₂ S cellulose derivatives (e.g. HEC) P ₂ of the embodiment preferably contains a basic like state ₂ of ammonia compound B.

The second polishing slurry S ₂ may contain a surfactant. May be used in the first polishing slurry S ₁ by the same as a surfactant. The technique disclosed herein can be implemented in a state where the second polishing slurry S ₂ is substantially free of a surfactant.

The second polishing slurry S ₂ may contain a chelating agent. As an example of a chelating agent may be used with a polishing slurry S ₁ by the same. The technique disclosed herein can be implemented in a state where the second polishing slurry S ₂ is substantially free of a chelating agent.

(Other ingredients)

In addition, the second polishing slurry S ₂ may further contain an organic acid, an organic acid salt, an inorganic acid, an inorganic acid salt, a preservative, a fungicide, and the like, as long as the effect of the present invention is not significantly hindered. Conventional additives in polishing slurry (typically polishing slurry used in polishing steps for silicon substrates). The second polishing slurry S _{2 is} similar to the first polishing slurry S ₁ , and preferably does not substantially contain an oxidizing agent.

<Grinding rate>

The above-described first polishing slurry S ₁ is preferably capable of displaying _two or more equal polishing of the second polishing slurry S, better show higher than the second polishing slurry S can _polishing rate. Thereby, a high-quality surface can be more efficiently realized for a plurality of silicon substrates having different resistivities. Here, the above-mentioned first polishing slurry S ₁ exhibits a higher polishing efficiency than the second polishing slurry S ₂ means that when the same object to be polished is polished under the same conditions, the first polishing slurry S _{1 is} used as the polishing slurry. The amount of polishing removal during the material removal is more than that when the second polishing slurry S _{2 is} used as the polishing slurry. Called the polishing slurry S ₁ first displays than the second polishing slurry S ₂ high polishing rate can be described later, for example, the method described in the embodiment examples can be determined polishing rate of each of the polishing slurry, by the geometric of And confirm. The silicon substrate used in the comparison of the polishing energy ratios is not particularly limited, and may be any silicon substrate such as P-, P ++, or P +++ in the examples described later. Since it is easy to increase the difference in polishing power and to grasp the relative relationship of polishing power, P-substrates can be used well.

The polishing energy rate of each polishing slurry can be controlled by, for example, the material of the polishing particles, the BET diameter of the polishing particles, the concentration of the polishing particles, the type of the water-soluble polymer, the concentration of the water-soluble polymer, the type of the basic compound, and the pH of the polishing slurry . For those skilled in the art, based on the description and technical common sense of the present specification including specific examples described later, the polishing energy rates of the first polishing slurry S ₁ and the second polishing slurry S ₂ or their relative relationships can be appropriately adjusted.

<Grinding>

The polishing method disclosed herein is to sequentially supply the first polishing slurry S ₁ and the second polishing slurry S ₂ to the silicon substrate of the polishing object during the polishing of the silicon substrate in order. The above-mentioned polishing method can be performed in a manner including, for example, the following operations.

That is, a silicon substrate as an object to be polished is set on a polishing device, and a polishing pad fixed to a platen (also referred to as a polishing platen) of the polishing device is performed on the surface of the object to be polished (object to be polished). polishing slurry supplied to the first S ₁ and the first stage of polishing. Typically, while the polishing slurry is continuously supplied, the polishing pad is pressed against the surface of the object to be polished to move the two relative to each other (for example, rotational movement). From S by the first polishing slurry of the polishing time T ₁ after the start of the _1, polishing slurry supplied to the polishing of the object of polishing slurry to the second switch S _2, T ₂ for the whole time in the second polishing slurry The material S ₂ grinds the object to be polished in the second stage.

The relationship between the polishing time T ₁ in the first stage and the polishing time T _{2 in} the second stage is not particularly limited. In the same state, the grinding time T ₁ in the first stage may be longer than the grinding time T ₂ in the second stage. That is, the polishing method disclosed herein can be supplied to the second plate of silicon based polishing slurry S ₂ of the object to be polished and the polishing time T ₂ is shorter than the first polishing slurry S is supplied to the silicon substrate ₁ and the polishing time T ₁ Implementation like this. In this way, by polishing the first polishing slurry S ₁ with a relatively high polishing energy for a relatively long time, it is possible to efficiently achieve a high-quality surface for a plurality of silicon substrates having different resistivities. The polishing method disclosed herein can be implemented, for example, such that the polishing time T ₁ in the first stage is 1.2 times or more (more preferably 1.5 times or more, such as 2 times or more) the grinding time T _{2 in} the second stage.

Although not particularly limited, the total polishing time (T ₁ + T ₂ ) of the first stage and the second stage may be, for example, 60 minutes or less. From the viewpoint of productivity, it is preferably 40 minutes or less, more preferably 20 minutes or less. . On the other hand, the total polishing time is based on the viewpoint of obtaining a high-quality surface. Usually, it is appropriate to set it to 3 minutes or more, preferably 5 minutes or more, and for example, 7 minutes or more.

Each polishing slurry may be in a concentrated form before being supplied to the object to be polished, that is, in the form of a concentrated liquid of the polishing slurry. The above-mentioned concentrated liquid can be grasped as a stock solution of a polishing slurry. The polishing slurry in such a concentrated form is advantageous from the viewpoints of convenience, cost reduction, and the like during manufacturing, distribution, and storage. The concentration ratio is not particularly limited, and may be, for example, about 2 to 100 times in volume conversion, and usually about 5 to 50 times (for example, 10 to 40 times) is appropriate.

This concentrated liquid can be diluted at a desired point to prepare a polishing slurry (operation slurry), and the polishing slurry can be used while being supplied to the object to be polished. The above-mentioned dilution is typically performed by adding water to the above-mentioned concentrated solution and mixing it.

The content of the abrasive particles in the concentrated liquid may be, for example, 50% by weight or less. From the viewpoint of the rationale of the concentrated liquid (for example, dispersion stability or filterability of the abrasive particles), the content of the abrasive particles in the concentrated liquid is usually preferably 45% by weight or less, more preferably 40% by weight or less. In addition, from the viewpoints of convenience, cost reduction, and the like during manufacturing, distribution, and storage, the content of the abrasive particles can be set to, for example, 0.5% by weight or more, preferably 1% by weight or more, and more preferably 3% by weight or more. 4% by weight or more. In a preferred aspect, the content of the abrasive particles may be, for example, 5 wt% or more, 10 wt% or more, 15 wt% or more, 20 wt% or more, and 30 wt% or more.

The grinding slurry or its concentrate used in the technology disclosed herein may be a one-dose form or a multi-dose form led by a two-dose form. For example, the polishing slurry may be prepared by mixing a portion A of at least the abrasive grains among the constituents of the polishing slurry with a portion B including the remaining components, and diluting the polishing slurry at an appropriate time as needed.

The method for preparing the polishing slurry or the concentrate thereof is not particularly limited. For example, a conventional mixing device such as a wing mixer, an ultrasonic disperser, and a homomixer can be used to mix each component contained in the polishing slurry or its concentrated solution. The form of mixing these components is not particularly limited, and for example, all the components may be mixed at a time, or they may be mixed in an appropriately set order.

In each polishing stage, the polishing slurry can be used in the state of being discarded once it is ground and used (so-called "source outflow"), or it can be recycled and reused. As an example of a method for recycling the polishing slurry, for example, a method of recovering the used polishing slurry discharged from the polishing device in a tank, and supplying the recovered polishing slurry to the polishing device again. The polishing method disclosed herein can be implemented in a state where both the first polishing slurry S ₁ used in the first stage and the second polishing slurry S ₂ used in the second stage are used in a source-by-flow manner.

The polishing pad used in the polishing method disclosed herein is not particularly limited. For example, a polishing pad of foamed polyurethane type, non-woven type, suede type, or the like can be used. Each polishing pad may or may not contain abrasive particles. It is generally preferred to use abrasive pads that do not contain abrasive particles.

The polishing method disclosed herein can be applied to any one of a preliminary polishing step and a finishing polishing step of a silicon substrate (such as a silicon single crystal wafer). Among them, it can be well applied to the finishing and polishing of silicon substrates after grinding and preliminary polishing. The surface roughness (arithmetic average roughness (Ra)) of the silicon substrate at the beginning of the first stage may be, for example, about 0.01 nm to 100 nm. The polishing method disclosed herein can be suitably applied to polishing (typically finishing polishing) a silicon substrate whose surface roughness Ra is adjusted to a surface state of, for example, about 0.01 nm to 100 nm by an upstream step. The surface roughness Ra of the silicon substrate can be measured using, for example, a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

The grinding apparatus used in the grinding method disclosed herein is configured to perform the above-mentioned first stage and the above-mentioned second stage on the same platen by switching the grinding slurry supplied to the same platen during grinding. The polishing device may be a two-sided polishing device that simultaneously grinds both sides of the object to be polished, or a single-sided polishing device that grinds only one side of the object to be polished. Although not particularly limited, the grinding method disclosed herein is applicable to fine grinding, As the polishing apparatus for performing the first stage and the second stage, a single-side polishing apparatus can be preferably used. When the preliminary grinding is performed before the first stage, the preliminary grinding may be performed using a double-sided grinding device or a single-sided grinding device, and for example, a double-sided grinding device is preferably used. The number of platens of each grinding device may be one or two or more. Each grinding device may be a single-piece grinding device configured to grind one grinding object at a time, or a batch grinding device capable of simultaneously grinding a plurality of grinding objects on the same platen.

The polishing method disclosed herein may include a step of cleaning the polishing object by supplying a cleaning solution to the polishing object on the same platen as the second stage polishing after polishing the polishing object. As the cleaning liquid, an aqueous solvent (for example, water) can be used. And, in an aqueous solvent can also be used to contain any components other than the second abrasive slurry ₂ used in the S component of the abrasive grains from the washing liquid.

The polishing object that has finished the second-stage polishing is typically washed. This washing | cleaning can be performed using an appropriate washing | cleaning liquid. The cleaning liquid used is not particularly limited, and general SC-1 cleaning liquids (ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and water (H ₂ O) mixed solution), SC-2 cleaning solution (HCl, H ₂ O ₂ and H ₂ O mixed solution) and the like. The temperature of the cleaning solution may be, for example, a room temperature (typically about 15 ° C to 25 ° C) or more and a range of up to about 90 ° C. From the viewpoint of improving the cleaning effect, a cleaning solution of about 50 ° C to 85 ° C can be preferably used. The above-mentioned washing is typically performed outside the grinding apparatus used for the grinding in the first stage and the second stage, that is, after the grinding object is removed from the grinding apparatus.

<Object to be polished>

The polishing method disclosed herein can be commonly applied to polishing a plurality of silicon substrates (typically silicon single crystal wafers) having different resistivities. The “commonly applicable” here means that the first stage of polishing the first polishing slurry S ₁ with the same composition and the second polishing slurry S ₂ polishing with the same composition are sequentially performed on the plurality of silicon substrates in this order. 2 stages. Thereby, using one polishing device configured to switchably supply the first polishing slurry S ₁ and the second polishing slurry S ₂ , a plurality of silicon substrates having different resistivities from each other are set to the polishing in any order or at any time. Mount and grind.

In the same state of the polishing method disclosed herein, the polishing time T _{1 in the} first stage and the polishing time T _{2 in the} second stage can be commonly applied to the same T ₁ and the same T ₂ for a plurality of types of silicon substrates having different resistivities. According to this aspect, for example, when a batch type polishing device is used, silicon substrates having different resistivities can be simultaneously polished on the same platen. In addition, since the same total polishing time can be applied regardless of the type of silicon substrate to be polished (for example, regardless of the resistivity of the silicon substrate), the polishing device can be used efficiently.

The polishing method disclosed herein can be commonly applied to polishing of a plurality of different types of silicon substrates having a resistivity of 10 times or more. It is particularly effective for polishing the above-mentioned plural kinds of silicon substrates with different resistivities of 20 times or more (preferably 100 times or more, more preferably 150 times or more, such as 200 times or more).

In a preferred state, the plurality of silicon substrates may include a resistivity of 1Ω. Silicon substrate above cm and resistivity have not reached 0.005Ω. cm silicon substrate. The polishing method disclosed in this article can be better applied to these silicon-based Grinding of plates (e.g. finishing grinding). For example, it can be commonly applied to a resistivity of 0.1Ω. cm or more, such as 1Ω. Silicon substrate above cm and resistivity less than 0.05Ω. cm, for example less than 0.005Ω. cm silicon substrate. Extraordinary is suitable for finishing polishing of these silicon substrates. The polishing method disclosed herein can be commonly applied to such silicon substrates with different resistivities, and the silicon substrates can be efficiently finished into high-quality surfaces.

<Polishing composition set>

According to the present specification, a polishing composition set which can be preferably used in the polishing method disclosed herein is provided. The polishing composition set includes at least a first composition Q ₁ and a second composition Q ₂ that are stored separately from each other. The first composition Q ₁ may be the first polishing slurry S ₁ used in the above-mentioned first stage or a concentrated solution thereof. The second composition Q ₂ may be the second polishing slurry S ₂ used in the second stage or a concentrated liquid thereof. The polishing method disclosed herein can be preferably implemented using the polishing composition set. Therefore, the above-mentioned polishing composition set can be suitably used for the polishing method disclosed herein or a method for manufacturing an abrasive including the polishing method. Each of the polishing compositions constituting the polishing composition set may be a one-dose form or a multi-dose form including a two-dose form. The multi-dose type polishing composition may be constituted by, for example, storing part A containing at least abrasive grains among the constituents of each polishing composition separately from part B containing the remaining ingredients, mixing the above-mentioned part A and the above-mentioned part B, and The composition for polishing or the polishing slurry is prepared by diluting at appropriate points as necessary.

As understood from the above description and the following examples, The matters disclosed in this specification include the following.

(1) A method of polishing the silicon wafer, which comprises the use disclosed herein, the polishing slurry according to any one of the first _polishing S (preferably the final polishing) resistivity less than 0.005 ohm. cm of silicon wafer.

(2) A polishing method for silicon wafers, which includes a common use for polishing with any of the first polishing slurry S ₁ disclosed herein (preferably for finishing polishing), and the resistivity does not reach 0.005Ω. cm silicon wafer and polishing (preferably finishing polishing) resistivity 1Ω. cm or more silicon wafer.

(3) The method for polishing a silicon wafer as described in (1) or (2) above, which comprises polishing with the first polishing slurry S ₁ described above, and then using any one of the first disclosed in this document on the same platen. 2 polishing slurry S ₂ polishing (preferably finishing polishing) the above silicon wafer.

(4) A method for manufacturing a polished silicon wafer (polished wafer), which includes any one of the polishing methods (1) to (3) above.

(5) A polishing composition, which is any of the first polishing slurry S ₁ or a concentrated liquid thereof disclosed herein, and is used when the resistivity does not reach 0.005Ω. cm silicon wafer polishing (preferably fine polishing).

(6) A polishing composition, which is any of the first polishing slurry S ₁ or a concentrated liquid thereof disclosed herein, and is commonly used for resistivity less than 0.005Ω. cm silicon wafer grinding (preferably fine grinding) and resistivity 1Ω. Grinding of silicon wafers above cm (preferably for finishing polishing).

(7) A polishing composition, which is any one of the second polishing slurry S ₂ or a concentrated solution thereof disclosed herein, and is continued to the polishing composition described in (5) or (6) above or After polishing the silicon wafer using the first polishing slurry S ₁ prepared by the polishing composition, the silicon wafer is polished on the same platen.

[Example]

Hereinafter, several embodiments related to the present invention will be described, but it is not intended to limit the present invention to those shown in the embodiments.

1. Preparation of grinding fluid (Slurry A)

In ion-exchanged water, colloidal silica (BET diameter 35 nm) as abrasive particles, hydroxyethyl cellulose (HEC; Mw140 × 10 ⁴ ) as a water-soluble polymer, and ammonia as a basic compound are prepared in Table 1. Shown composition A.

(Slurry B)

In ion-exchanged water, a slurry B having a composition shown in Table 1 was prepared including colloidal silicon oxide (BET diameter 35 nm), HEC (Mw120 × 10 ⁴ ), and tetramethylammonium hydroxide (TMAH).

(Slurry C ~ E, J, K)

In ion-exchanged water, colloidal silica (BET diameter 35nm), PVA, PVP, and KOH were used to prepare slurry C ~ E, J, and K having the composition shown in Table 1. Table 1 shows the Mw of PVA and PVP used in the preparation of each slurry. The saponification degree of PVA used for the preparation of these slurries are all It is above 98 mol%. In addition, the PVP used in the preparation of these slurries are all homopolymers of vinylpyrrolidone. C10PEO5 in Table 1 represents polyoxyethylene decyl ether having an average addition mole number of 5 to ethylene oxide.

(Slurry F ~ H)

In the ion-exchanged water, colloidal silica (BET diameter: 35nm), PVA main chain-PVP graft copolymer, and KOH were used to prepare slurry F ~ H having the composition shown in Table 1. Table 1 shows the Mw of the main chain and side chain of the PVA main chain-PVP graft copolymer used in the preparation of each slurry. These graft copolymers are all saponification degree of PVA constituting the main chain of more than 98 mole%, and the PVP constituting the test chain is a homopolymer of vinylpyrrolidone.

(Slurry I)

Colloidal silica (BET diameter: 35 nm), HEC (Mw140 × 10 ⁴ ), and KOH were included in the ion-exchanged water to prepare slurry I having the composition shown in Table 1.

The BET diameter of colloidal silica is measured using a surface area measuring device manufactured by Micro Materials Co., Ltd. under the trade name "Flow Sorb II 2300". In addition, all the slurry A to I were prepared to have a pH within a range of 10 to 11.

2. Polishing of silicon wafers

The following three types of silicon substrates (300 mm diameter silicon single crystal wafers) were used for the polishing test.

P-: resistivity 1Ω. Above 100 cm. cm

P ++: Resistivity 0.006Ω. Above cm is less than 0.010Ω. cm

P +++: The resistivity does not reach 0.002Ω. cm

<Preparation grinding step>

A preliminary polishing slurry (operation slurry) containing 0.7% by weight of colloidal silica (BET diameter 35 nm), 0.04% by weight of TMAH, and 0.25% by weight of piperidine was prepared in ion-exchanged water. Using this preliminary polishing slurry, the silicon substrate to be polished was pre-polished under the following conditions, thereby adjusting the surface roughness Ra of each silicon substrate (P-, P ++, P +++) to about 0.4 nm.

[Preparative grinding conditions]

Grinding device: Single-side grinder manufactured by Fujitsu Machinery Co., Ltd., model "SPM-15"

Grinding load: 320g / cm ²

Number of platen rotation: 30rpm

Number of indenter rotation: 30rpm

Polishing pad: made by NITTA HAAS, non-woven type, product name "SUBA600"

Supply rate: 6 liters / minute (recycling)

Holding temperature of grinding environment: 23 ℃

(Wash)

Remove the pre-polished silicon substrate from the polishing device, and wash it with NH ₄ OH (29%): H ₂ O ₂ (31%): deionized water (DIW) = 1: 1: 15 (volume ratio) Liquid washing (SC-1 washing). More specifically, two washing tanks equipped with an ultrasonic oscillator with a frequency of 950 kHz were prepared, and the above-mentioned washing liquid was stored in each of the first and second washing tanks and maintained at 80 ° C., respectively. With each of the above-mentioned ultrasonic oscillators operating, the pre-polished silicon substrate was immersed in the first cleaning tank for 5 minutes, and then passed through a cleaning tank using ultrapure water and ultrasonic waves, and immersed in the second cleaning 5 minutes in the bath.

<Finishing step>

The slurry A to K were directly used as a polishing liquid (operation slurry), and the cleaned silicon substrate was subjected to finishing polishing under the following conditions.

[Finishing and grinding conditions]

Grinding object: as shown in Table 2

Grinding device: Single-side grinder manufactured by Fujitsu Machinery Co., Ltd., model "SPM-15"

Grinding load: 150g / cm ²

Number of platen rotation: 40rpm

Number of indenter rotation: 40rpm

Polishing pad: made by NITTA HAAS, suede type, product name "Supreme RN-H"

Supply rate: 0.5 liters / minute (for source use)

Holding temperature of grinding environment: 20 ℃

Grinding time: 7 minutes in stage 1, followed by 3 minutes in stage 2

(However, the first stage of Examples 8 to 11 is continued for 10 minutes, and the second stage is not performed.)

Specifically, the following finishing grinding steps are performed.

(example 1)

The silicon substrate was set on the above-mentioned polishing apparatus, and the slurry C was supplied to start polishing in the first stage. After 7 minutes from the start of the first stage, the supplied slurry was switched from slurry C to slurry A, and the second stage of polishing was continued. After 3 minutes have passed since the start of the second stage, the supply of slurry A and the operation of the grinding device were stopped.

(Examples 2 ~ 7, 12, 13)

A silicon substrate was polished in the same manner as in Example 1 except that the slurry supplied in the first stage was changed to that shown in Table 2.

(Examples 8 to 11)

The silicon substrate was set on the above-mentioned polishing apparatus, and the slurry shown in Table 2 was supplied to start polishing. After 10 minutes have passed since the start of grinding, the supply of slurry and the operation of the grinding device are stopped.

The silicon substrate after finishing polishing is removed from the polishing device, and the cleaning is performed in the same manner as the cleaning after the preliminary polishing. In this way, the silicon wafers obtained by the finishing polishing of Examples 1 to 13 were obtained.

3. Evaluation (Measurement of turbidity level)

Using the wafer polishing system of ADE Corporation, trade name "AWIS 3110", the turbidity level [ppm] of the silicon wafer after finishing polishing in Examples 1 to 11 was measured. The results are shown in the "Haze" column in Table 2.

(Measurement of grinding energy)

From the difference in weight of the silicon substrate before and after finishing polishing and the area of the object to be polished, determine the thickness (amount of polishing removal) removed in the finishing polishing step, and divide it by the polishing time (here, 10 minutes) to calculate the unit per time Average polishing removal (polishing energy). The obtained value was converted into a relative value when the polishing power of Example 1 was set to 1.00 for each silicon substrate. The results are shown in the "grinding power" column of Table 2.

And, for each of Examples 1 to 10, 12, and 13, the P-substrate / P +++ substrate was calculated by dividing the polishing energy rate [nm / min] of the P-substrate by the polishing energy rate [nm / min] of the P +++ substrate. The polishing power ratio (that is, the ratio of the polishing power of the P-substrate to the polishing power of the P +++ substrate). The results are shown in the "grinding energy ratio" column of Table 2.

For each example shown in Table 2, the column "-" of the turbidity and polishing power indicates that a polishing test was not performed on a silicon substrate of this type.

Furthermore, instead of the slurry A of Example 8, the silicon substrate was polished using each of the slurry D, E, and G to K. After the polishing energy was calculated in the same manner as described above, as shown in Table 3, it was confirmed that all of them showed a specific ratio. High grinding efficiency.

As shown in Table 1, an example in which the first-stage and second-stage polishing are performed by switching the first-stage slurry C to K containing the water-soluble polymer P _{1 to} the second-stage slurry having a lower polishing efficiency. In 1 ~ 7,12,13, with the same polishing process, for the polishing of silicon wafers with any resistivity, low-turbidity grade surfaces comparable to those in Example 8 were also obtained. Compared with Examples 1 to 3 and 7 using slurry C to E and I, Examples 4 to 6 using slurry F to H showed a tendency to obtain a surface with a lower turbidity grade. In addition, compared with Example 8 in which only slurry A was polished, in Examples 1 to 7, 12, and 13, the polishing efficiency of the P +++ substrate was approximately doubled in polishing. And as can be seen from the comparison of the polishing energy ratios of Examples 1-7, 12, 13 and Example 8, compared with Example 8, Examples 1-7, 12, 13 alleviate the polishing caused by the resistivity of the silicon wafer. The difference in power.

On the other hand, in Example 11 where only slurry B was polished, the polishing efficiency was high, but the turbidity level reduction effect was insufficient in either of the P-substrate and P ++ substrate polishing. In Examples 9 and 10 where only slurry C or slurry F was polished, the turbidity level in the polishing of the P-substrate could not be sufficiently reduced. low.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of patent applications. The technology described in the scope of the patent application includes various modifications and changes of the specific examples illustrated above.

Claims (12)

A method for polishing a silicon substrate, which comprises sequentially supplying a first polishing slurry S ₁ and a second polishing slurry S ₂ to the silicon substrate of an object to be polished alternately during the polishing of the silicon substrate. ₁ contains abrasive particles A ₁ and a water-soluble polymer P _1. The polishing energy rate of the first polishing slurry S ₁ is higher than the polishing energy rate of the second polishing slurry S ₂ . The polishing method according to claim 1, wherein the first polishing slurry S ₁ is a water-soluble polymer P _{1 having} a concentration of 0.001% by weight or more. The polishing method according to claim 1 or 2, wherein the water-soluble polymer P ₁ includes a vinyl alcohol-based polymer chain. The polishing method according to any one of claims 1 to 3, wherein the water-soluble polymer P ₁ includes an N-vinyl polymer chain. The polishing method according to any one of claims 1 to 4, wherein the aforementioned first polishing slurry S ₁ contains an alkali metal hydroxide as the basic compound B ₁ . The polishing method according to any one of claims 1 to 5, wherein the BET diameter of the aforementioned abrasive particles A _{1 does} not reach 60 nm. The polishing method according to any one of claims 1 to 6, wherein the second polishing slurry S ₂ contains abrasive particles A ₂ and a water-soluble polymer P ₂ , and the second polishing slurry S ₂ has high water solubility. The concentration of the molecule P ₂ is higher than the concentration of the water-soluble polymer P _{1 in} the first polishing slurry S ₁ . The polishing method according to any one of items 1 to 7 as a request, wherein the second polishing slurry containing abrasive grains S ₂ A _2, the second polishing slurry ₂ S content of the abrasive grains of the A ₂ of 0.5 wt% the following. The polishing method of any one of claims 1 to 8 is generally applicable to a resistivity of 1Ω. Silicon substrate above cm and resistivity have not reached 0.005Ω. cm silicon substrate. One kind of polishing composition, which based polishing composition used in the polishing method of a request entry as any one of 1 to 9, and the first polishing slurry is ₁ S or concentrate. A polishing composition is the polishing composition used in the polishing method according to any one of claims 1 to 9, and is the aforementioned second polishing slurry S ₂ or a concentrated solution thereof. A polishing composition set, which is the polishing composition set used in the polishing method according to any one of claims 1 to 9, and includes the first composition of the first polishing slurry S ₁ or a concentrated liquid thereof. The product Q ₁ and the second composition Q _{2 of} the second polishing slurry S ₂ or the concentrated liquid thereof, the first composition Q ₁ and the second composition Q ₂ are stored separately from each other.